300 IU vs. 200 IU of OnabotulinumtoxinA for detrusor overactivity

Botulinum toxin is probably the newest addition in the treatment armamentarium for overactive bladder , but, despite its late FDA approval, a significant experience exists in several centers around the world with this type of treatment. Because of its experimental status, the treatment with botulinum toxin is still lacking the much needed standardization, allowing for a great variety when it comes to dosing, frequency and injection sites. Although the efficacy of this treatment is well proven , the correct dose for each particular condition is still a matter of debate, despite a vast number of dose finding clinical trials. The authors of this paper report data from a retrospective analysis done in a single center with significant experience [1, 2]. The idea behind their work is to assess the efficacy of treatment with botulinum toxin, using a significantly lower dose, in patients with neurogenic or idiopathic detru-sor overactivity. The rationale behind the plan to decrease the toxin dose is based on strong evidence from literature, which led to a change in the standard of care offered in their institution about five years ago. The study population included patients with proven detrusor overactivity who started treatment with the standard dose of 300 IU and were then shifted to the lower dose of 200 IU. The results were then compared, with the main focus set on efficacy. The tools for this assessment were limited to interview and bladder diary, both being subject to interpretation and potential subjectivity. This raises the discussion of the objectivity of the conclusions that are not supported by urodynamic measurements. This could reveal increased storage pressures and other potentially dangerous conditions that don't have a clinical expression for the moment but may lead to serious complications, especially in the neurogenic bladder group. It is a known saying that the bladder is an unreliable witness, and such investigation protocol leaves a great amount of matters unaddressed. There are many aspects which raise questions, such [3] as injecting or avoiding the trigone, the underlying condition behind the neurogenic bladder and the concomitant medication of each patient. Another aspect which is not clear is the previous [4] treatment each patient had for detrusor overactivi-ty, which could further bias the response and toler-ability to botulinum toxin. A classical talk related to the treatment for detrusor overactivity is about adherence and persistence. These aspects are not discussed by the authors, although it seems …